It is Northern Ireland that provides the classic contemporary demonstration of Clausewitzian principles in action. In 1974 the Ulster Protestants rej… - Correlli Barnett

That Clausewitz lives, and will live, is equally shown in such cases as the former Yugoslavia, where Nato has simply frozen a war which will certainly break out again if and when the intervention forces leave; or Israel–Palestine, where the political relations between Jew and Arab reflect the military outcome of past wars, where the conflict of interest is essentially irreconcilable, and where therefore policy and violence will continue to go hand in hand.
What may therefore be safely predicted is that over the next 170 years the world will continue to be an arena of complex rivalries and direct collisions of interest rather than a "world order" or a "world community", and that human groups engaged in such rivalries will from time to time resort to force as an instrument of their politics. What weapons will be then available, and what tactics will consequently be employed, only a fool would pretend to guess. It will be remarked that so far I have not mentioned the United Nations Organisation, that expensive figment of liberal wishful thinking. I have done so now.

The new German conception of organizing and planning opened the modern epoch of war. Nothing like the minutely dovetailed plans, routes, and timetables of the mobilization and Aufmarsch of 1870 had been seen before. Thus an army had become the professional and organizational peer of modern history.

[T]he essential and constant factor common to all three national academies [in Britain, France and America] is the indoctrination with tradition: potent emotional conditioning in military myth, habits, and attitudes. There are the physical symbols and reminders: engraved tablets of the glorious dead; the museums; the assembled iconography of illustrious graduates; statues; guns... At all three academies there are songs, slang, customs and ceremonies that link each annual class together for the rest of their army life... This indoctrination has grown out of history rather than been artificially created, but it may be doubted whether psychologists or sociologists could improve on it. Upon this mental sub-structure, purely neo-feudalist with its emphasis on glory, gallantry, honour, duty, and patriotism, is built functional and technical training, both concurrently at the academies, and later in schools of application. But it is this indoctrination, together with drill and discipline, that turns civilians into soldiers. Without it there would be no difference between a general in a defence ministry and a high executive in a business cartel. In terms therefore of creating the common character of the military elite, this constant factor of conditioning inside cadet colleges has been of greater importance than the changing detail and emphasis of academic curriculum and military training.